Source code for gammapy.astro.darkmatter.spectra

# Licensed under a 3-clause BSD style license - see LICENSE.rst
"""Dark matter spectra."""
import numpy as np
import astropy.units as u
from astropy.table import Table
from gammapy.maps import MapAxis, RegionNDMap
from gammapy.modeling import Parameter
from gammapy.modeling.models import (
    SPECTRAL_MODEL_REGISTRY,
    SpectralModel,
    TemplateNDSpectralModel,
)
from gammapy.utils.scripts import make_path

__all__ = ["PrimaryFlux", "DarkMatterAnnihilationSpectralModel"]


[docs]class PrimaryFlux(TemplateNDSpectralModel): """DM-annihilation gamma-ray spectra. Based on the precomputed models by Cirelli et al. (2016). All available annihilation channels can be found there. The dark matter mass will be set to the nearest available value. The spectra will be available as `~gammapy.modeling.models.TemplateNDSpectralModel` for a chosen dark matter mass and annihilation channel. Using a `~gammapy.modeling.models.TemplateNDSpectralModel` allows the interpolation between different dark matter masses. Parameters ---------- mDM : `~astropy.units.Quantity` Dark matter particle mass as rest mass energy. channel: str Annihilation channel. List available channels with `~gammapy.spectrum.PrimaryFlux.allowed_channels`. References ---------- * `2011JCAP...03..051 <https://ui.adsabs.harvard.edu/abs/2011JCAP...03..051C>`_ * Cirelli et al (2016): http://www.marcocirelli.net/PPPC4DMID.html """ channel_registry = { "eL": "eL", "eR": "eR", "e": "e", "muL": r"\[Mu]L", "muR": r"\[Mu]R", "mu": r"\[Mu]", "tauL": r"\[Tau]L", "tauR": r"\[Tau]R", "tau": r"\[Tau]", "q": "q", "c": "c", "b": "b", "t": "t", "WL": "WL", "WT": "WT", "W": "W", "ZL": "ZL", "ZT": "ZT", "Z": "Z", "g": "g", "gamma": r"\[Gamma]", "h": "h", "nu_e": r"\[Nu]e", "nu_mu": r"\[Nu]\[Mu]", "nu_tau": r"\[Nu]\[Tau]", "V->e": "V->e", "V->mu": r"V->\[Mu]", "V->tau": r"V->\[Tau]", } table_filename = "$GAMMAPY_DATA/dark_matter_spectra/AtProduction_gammas.dat" tag = ["PrimaryFlux", "dm-pf"] def __init__(self, mDM, channel): self.table_path = make_path(self.table_filename) if not self.table_path.exists(): raise FileNotFoundError( f"\n\nFile not found: {self.table_filename}\n" "You may download the dataset needed with the following command:\n" "gammapy download datasets --src dark_matter_spectra" ) else: self.table = Table.read( str(self.table_path), format="ascii.fast_basic", guess=False, delimiter=" ", ) self.channel = channel # create RegionNDMap for channel masses = np.unique(self.table["mDM"]) log10x = np.unique(self.table["Log[10,x]"]) mass_axis = MapAxis.from_nodes(masses, name="mass", interp="log", unit="GeV") log10x_axis = MapAxis.from_nodes(log10x, name="energy_true") channel_name = self.channel_registry[self.channel] region_map = RegionNDMap.create( region=None, axes=[log10x_axis, mass_axis], data=self.table[channel_name] ) interp_kwargs = {"extrapolate": True, "fill_value": 0, "values_scale": "lin"} super().__init__(region_map, interp_kwargs=interp_kwargs) self.mDM = mDM self.mass.frozen = True @property def mDM(self): """Dark matter mass.""" return u.Quantity(self.mass.value, "GeV") @mDM.setter def mDM(self, mDM): unit = self.mass.unit _mDM = u.Quantity(mDM).to(unit) _mDM_val = _mDM.to_value(unit) min_mass = u.Quantity(self.mass.min, unit) max_mass = u.Quantity(self.mass.max, unit) if _mDM_val < self.mass.min or _mDM_val > self.mass.max: raise ValueError( f"The mass {_mDM} is out of the bounds of the model. Please choose a mass between {min_mass} < `mDM` < {max_mass}" ) self.mass.value = _mDM_val @property def allowed_channels(self): """List of allowed annihilation channels.""" return list(self.channel_registry.keys()) @property def channel(self): """Annihilation channel as a string.""" return self._channel @channel.setter def channel(self, channel): if channel not in self.allowed_channels: raise ValueError( f"Invalid channel: {channel}\nAvailable: {self.allowed_channels}\n" ) else: self._channel = channel
[docs] def evaluate(self, energy, **kwargs): """Evaluate the primary flux.""" mass = {"mass": self.mDM} kwargs.update(mass) log10x = np.log10(energy / self.mDM) dN_dlogx = super().evaluate(log10x, **kwargs) dN_dE = dN_dlogx / (energy * np.log(10)) return dN_dE
[docs]class DarkMatterAnnihilationSpectralModel(SpectralModel): r"""Dark matter annihilation spectral model. The gamma-ray flux is computed as follows: .. math:: \frac{\mathrm d \phi}{\mathrm d E} = \frac{\langle \sigma\nu \rangle}{4\pi k m^2_{\mathrm{DM}}} \frac{\mathrm d N}{\mathrm dE} \times J(\Delta\Omega) Parameters ---------- mass : `~astropy.units.Quantity` Dark matter mass. channel : str Annihilation channel for `~gammapy.astro.darkmatter.PrimaryFlux`, e.g. "b" for "bbar". See `PrimaryFlux.channel_registry` for more. scale : float Scale parameter for model fitting. jfactor : `~astropy.units.Quantity` Integrated J-Factor needed when `~gammapy.modeling.models.PointSpatialModel` is used. z: float Redshift value. k: int Type of dark matter particle (k:2 Majorana, k:4 Dirac). Examples -------- This is how to instantiate a `DarkMatterAnnihilationSpectralModel` model:: >>> import astropy.units as u >>> from gammapy.astro.darkmatter import DarkMatterAnnihilationSpectralModel >>> channel = "b" >>> massDM = 5000*u.Unit("GeV") >>> jfactor = 3.41e19 * u.Unit("GeV2 cm-5") >>> modelDM = DarkMatterAnnihilationSpectralModel(mass=massDM, channel=channel, jfactor=jfactor) # noqa: E501 References ---------- * `2011JCAP...03..051 <https://ui.adsabs.harvard.edu/abs/2011JCAP...03..051C>`_ """ THERMAL_RELIC_CROSS_SECTION = 3e-26 * u.Unit("cm3 s-1") """Thermally averaged annihilation cross-section""" scale = Parameter( "scale", 1, unit="", interp="log", ) scale._is_norm = True tag = ["DarkMatterAnnihilationSpectralModel", "dm-annihilation"] def __init__(self, mass, channel, scale=scale.quantity, jfactor=1, z=0, k=2): self.k = k self.z = z self.mass = u.Quantity(mass) self.channel = channel self.jfactor = u.Quantity(jfactor) self.primary_flux = PrimaryFlux(mass, channel=self.channel) super().__init__(scale=scale)
[docs] def evaluate(self, energy, scale): """Evaluate dark matter annihilation model.""" flux = ( scale * self.jfactor * self.THERMAL_RELIC_CROSS_SECTION * self.primary_flux(energy=energy * (1 + self.z)) / self.k / self.mass / self.mass / (4 * np.pi) ) return flux
[docs] def to_dict(self, full_output=False): """Convert to dictionary.""" data = super().to_dict(full_output=full_output) data["spectral"]["channel"] = self.channel data["spectral"]["mass"] = self.mass.to_string() data["spectral"]["jfactor"] = self.jfactor.to_string() data["spectral"]["z"] = self.z data["spectral"]["k"] = self.k return data
[docs] @classmethod def from_dict(cls, data): """Create spectral model from a dictionary. Parameters ---------- data : dict Dictionary with model data. Returns ------- model : `DarkMatterAnnihilationSpectralModel` Dark matter annihilation spectral model. """ data = data["spectral"] data.pop("type") parameters = data.pop("parameters") scale = [p["value"] for p in parameters if p["name"] == "scale"][0] return cls(scale=scale, **data)
[docs]class DarkMatterDecaySpectralModel(SpectralModel): r"""Dark matter decay spectral model. The gamma-ray flux is computed as follows: .. math:: \frac{\mathrm d \phi}{\mathrm d E} = \frac{\Gamma}{4\pi m_{\mathrm{DM}}} \frac{\mathrm d N}{\mathrm dE} \times J(\Delta\Omega) Parameters ---------- mass : `~astropy.units.Quantity` Dark matter mass. channel : str Annihilation channel for `~gammapy.astro.darkmatter.PrimaryFlux`, e.g. "b" for "bbar". See `PrimaryFlux.channel_registry` for more. scale : float Scale parameter for model fitting jfactor : `~astropy.units.Quantity` Integrated J-Factor needed when `~gammapy.modeling.models.PointSpatialModel` is used. z: float Redshift value. Examples -------- This is how to instantiate a `DarkMatterAnnihilationSpectralModel` model:: >>> import astropy.units as u >>> from gammapy.astro.darkmatter import DarkMatterDecaySpectralModel >>> channel = "b" >>> massDM = 5000*u.Unit("GeV") >>> jfactor = 3.41e19 * u.Unit("GeV cm-2") >>> modelDM = DarkMatterDecaySpectralModel(mass=massDM, channel=channel, jfactor=jfactor) # noqa: E501 References ---------- * `2011JCAP...03..051 <https://ui.adsabs.harvard.edu/abs/2011JCAP...03..051C>`_ """ LIFETIME_AGE_OF_UNIVERSE = 4.3e17 * u.Unit("s") """Use age of univserse as lifetime""" scale = Parameter( "scale", 1, unit="", interp="log", ) scale._is_norm = True tag = ["DarkMatterDecaySpectralModel", "dm-decay"] def __init__(self, mass, channel, scale=scale.quantity, jfactor=1, z=0): self.z = z self.mass = u.Quantity(mass) self.channel = channel self.jfactor = u.Quantity(jfactor) self.primary_flux = PrimaryFlux(mass, channel=self.channel) super().__init__(scale=scale)
[docs] def evaluate(self, energy, scale): """Evaluate dark matter decay model.""" flux = ( scale * self.jfactor * self.primary_flux(energy=energy * (1 + self.z)) / self.LIFETIME_AGE_OF_UNIVERSE / self.mass / (4 * np.pi) ) return flux
[docs] def to_dict(self, full_output=False): data = super().to_dict(full_output=full_output) data["spectral"]["channel"] = self.channel data["spectral"]["mass"] = self.mass.to_string() data["spectral"]["jfactor"] = self.jfactor.to_string() data["spectral"]["z"] = self.z return data
[docs] @classmethod def from_dict(cls, data): """Create spectral model from dictionary. Parameters ---------- data : dict Dictionary with model data. Returns ------- model : `DarkMatterDecaySpectralModel` Dark matter decay spectral model. """ data = data["spectral"] data.pop("type") parameters = data.pop("parameters") scale = [p["value"] for p in parameters if p["name"] == "scale"][0] return cls(scale=scale, **data)
SPECTRAL_MODEL_REGISTRY.append(DarkMatterAnnihilationSpectralModel) SPECTRAL_MODEL_REGISTRY.append(DarkMatterDecaySpectralModel)